1. Field of the Invention
The present invention relates to a light-receiving member having a sensitivity to electromagnetic waves such as light (which herein refers to light in a broad sense and indicates ultraviolet rays, visible rays, infrared rays, X-rays, .gamma.-rays, etc.), and more particularly to a light-receiving member that can be preferably used in electrophotography.
2. Related Background Art
In the field of image formation, photoconductive materials capable of forming light-receiving layers in light-receiving members are required to have properties such that they are highly sensitive, have a high SN ratio [light current (Ip)/dark current (Id)], have absorption spectra suited to spectral characteristics of electromagnetic waves to be radiated, have a high response to light, have the desired dark resistance and are harmless to human bodies when used. In particular, in the case of electrophotographic light-receiving members set in electrophotographic apparatus used in offices, the above safety in their use is an important point.
Photoconductive materials recently attracting notice from such a viewpoint include amorphous silicon (hereinafter "a-Si"). For example, German Patent Applications Laid-open No. 27 46 967 and No. 28 55 718 disclose its application in electrophotographic light-receiving members.
Japanese Patent Application Laid-open No. 56-83746 discloses an electrophotographic light-receiving member comprising an a-Si photoconductive layer secondary region containing a halogen atom as a component. This publication reports that incorporation of 1 to 40 atom % of halogen atoms into a-Si enables compensation of dangling bonds and decrease of localized level density in energy gaps to accomplish electrical and optical properties suitable as a photoconductive layer secondary region of an electrophotographic light-receiving member.
Meanwhile, amorphous silicon carbide (hereinafter "a-SiC") is known to promise a high heat resistance or surface hardness, have a higher dark resistance than a-Si and enable change of optical band gaps over a range of 1.6 to 2.8 eV depending on the content of carbon. Japanese Patent Application Laid-open No. 54-145540 discloses an electrophotographic light-receiving member in which a photoconductive layer is comprised of such an a-SiC. This publication shows that superior electrophotographic performances with a high dark resistance and a good photosensitivity can be exhibited when a-Si containing 0.1 to 30 atom % of carbon as a chemical modifier is used as a photoconductive layer of an electrophotographic light-receiving member.
Japanese Patent Publication No. 63-35026 also discloses an electrophotographic photosensitive member comprised of an a-Si intermediate layer containing a carbon atom and at least one of a hydrogen atom and a fluorine atom [hereinafter "a-SiC(H,F)] and an a-Si photoconductive layer, where the a-Si intermediate layer containing at lest a hydrogen atom and/or a fluorine atom is provided so that cracking or separation of the a-Si photoconductive layer can be decreased without damage of photoconductive properties.
These techniques have made it possible to obtain electrophotographic light-receiving members having good electrical properties.
The conventional electrophotographic light-receiving members having a photoconductive layer comprised of a-SiC have individually achieved improvements in properties in respect of electrical, optical and photoconductive properties and service environmental properties and also in respect of stability with time and durability. Under existing circumstances, however, there is room for further improvements to make their overall properties better.
Particularly in recent years, with spread of high-speed copying machines, digital copying machines, full-color copying machines and high-speed LBP, electrophotographic apparatus are sought to achieve higher image quality, higher speed and higher durability. As a result, electrophotographic light-receiving members are now required to be more free from faulty memory or images than ever and, in addition to further improvements in electrical properties or photoconductive properties, to raise charge performance and sensitivity to a level required when used at a high speed and at the same time achieve a great improvement in durability.
However, in an attempt to simultaneously achieve higher speed and higher dark resistance, more than a few conventional electrophotographic light-receiving members have been involved in difficulties such that residual potential is often seen to remain during their use and the use of light-receiving members of this type over a long period of time causes a phenomenon of what is called "ghost", which is an after-image caused by accumulation of fatigue due to repeated use.
For example, in conventional electrophotographic light-receiving members in which, for example, a blocking layer is provided in order to block injection of electrical charges from a support, it has been necessary to more efficiently block the injection of electrical charges by decreasing carbon content in the blocking layer or increasing the amount of doping of boron so that blocking performance can be improved, as means for improving blocking performance and achieving an improvement in charge performance and an improvement in dark decay. Any of these methods are effective means for improving blocking performance. They, however, have had the problem that side effects such as a lowering of the adhesion between a deposited film and the support or other layer such as photoconductive layer and a lowering of charge performance may occur.